KLKB1 and deep vein thrombosis: Recent genetic studies of deep vein thrombosis (DVT) reported that several common single nucleotide polymorphisms (SNPs) in the F11, KLKB1, and CYP4V2 region (not including FAM149A) were associated with DVT and plasma FXI antigen levels (individuals with FXI antigen in 90 percentile having a 2-fold increased risk for DVT) [3].